Vaccines are the most effective measure to prevent deaths and illness from infectious diseases. Nevertheless, the efficacy of several paediatric vaccines is lower in low-income and middle-income countries (LMICs), where mortality from vaccine-preventable infections remains high. Vaccine efficacy can also be decreased in adults in the context of some common comorbidities. Identifying and correcting the specific causes of impaired vaccine efficacy is of substantial value to global health. Iron deficiency is the most common micronutrient deficiency worldwide, affecting more than 2 billion people, and its prevalence in LMICs could increase as food security is threatened by the COVID-19 pandemic. In this Viewpoint, we highlight evidence showing that iron deficiency limits adaptive immunity and responses to vaccines, representing an under-appreciated additional disadvantage to iron deficient populations. We propose a framework for urgent detailed studies of iron-vaccine interactions to investigate and clarify the issue. This framework includes retrospective analysis of newly available datasets derived from trials of COVID-19 and other vaccines, and prospective testing of whether nutritional iron interventions, commonly used worldwide to combat anaemia, improve vaccine performance.

中文翻译：

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疫苗功效和缺铁：一对交织在一起的东西？

疫苗是预防传染病死亡和患病的最有效措施。然而，在低收入和中等收入国家 (LMIC)，一些儿科疫苗的功效较低，疫苗可预防感染的死亡率仍然很高。在某些常见合并症的情况下，成人的疫苗效力也会降低。查明和纠正疫苗效力受损的具体原因对全球健康具有重大价值。缺铁症是全世界最常见的微量营养素缺乏症，影响超过 20 亿人，随着 COVID-19 大流行病威胁粮食安全，缺铁症在中低收入国家的患病率可能会增加。在这个观点中，我们强调证据表明缺铁会限制适应性免疫和对疫苗的反应，代表缺铁人群的一个未被充分认识的额外劣势。我们提出了一个紧急详细研究铁-疫苗相互作用的框架，以调查和澄清这个问题。该框架包括对来自 COVID-19 和其他疫苗试验的新可用数据集的回顾性分析，以及对全球普遍用于抗击贫血的营养铁干预措施是否能提高疫苗性能的前瞻性测试。